1. Field of the Invention
The present invention relates to a method for computer simulation for evaluating immunity characteristics or emission characteristics, and relates also to a method for generating a transmission line model.
2. Description of Related Art
Conventionally, in the designing of a structure (vehicle, railroad vehicle, marine vessel, aircraft, or the like) having a transmission line such as an electric conductor wire harness, or in the designing of various electric components mounted in it, as means for evaluating their immunity characteristics or immunity characteristics, EMC (electromagnetic compatibility) computer simulation is widely used beside measurement bench marks.
Examples of prior art related to what is just mentioned are found in Japanese Patent Application published as No. 2015-75390 by the present inventor, Japanese Patent Application published as No. 2013-242649, and an article by Hiroya TANAKA et al., “Simulation Models of BCI (bulk current injection) test systems,” Technical Research Report. EMCJ, Environmental Electromagnetic Engineering, The Institute of Electronics, Information and Communication Engineers, Aug. 31, 2012, Volume 112, Issue 201, pp. 47-50).
However, in conventional EMC computer simulation, wire harness structures for measurement bench marks that are subject to strict restrictions are modeled as they are. For example, in a case where a measurement bench mark requires that the total wire harness length be 1700 to 2000 mm and that the number of EMC noise injection points be three (positions at the distances of 150 mm, 450 mm, and 750 mm from a DUT), the wire harness structure for EMC computer simulation is subject to restrictions similar to those in the measurement bench mark. This results in insufficient coverage of phenomena that actually occur, making it difficult to evaluate actual immunity characteristics or emission characteristics properly.
Moreover, in conventional EMC computer simulation, a wire harness model is represented by a single characteristic impedance. This results in not small deviations between measured values and simulated values.